Grave fears for hiker missing in Mount Kosciuszko National Park for five days as his heartbroken family issues desperate plea

The sister of a missing university student who vanished without a trace while on a hiking trip has issued a moving plea to authorities as she clings to hope he will be found safely.

It’s been five days since Hadi Nazari, 23, separated from friends to take photos along the Hannels Spur Trail between Khancoban and Thredbo in Mount Kosciuszko National Park in the NSW Snowy Mountains on Boxing Day.

The Melbourne student told the group he would meet them at the Geehi campsite along the route.

When Nazari did not arrive, his friends searched for him before alerting authorities.

Specialist police units and SES crews have been searching the dense bushland on the ground and in the air for the past five days.

Mr Nazari, an experienced bushwalker who turns 23 today, carried a tent, sleeping bag and a phone.

The group departed Melbourne on December 22 with plans to return home on Boxing Day.

On Christmas Day, Mr Nazari texted his sister Zahra using a friend’s phone to pass on a simple message: “I’ll be home tomorrow.”

Student Hadi Nazari has been missing from Mount Kosciuszcko National Park for five days after being separated from his friends

Sister Zahra Nazari has expressed her sincere concerns for her brother's well-being

Sister Zahra Nazari has expressed her sincere concerns for her brother’s well-being

Ms Nazari fears her brother is overwhelmed by his surroundings and urges authorities to continue the search.

“It’s a remote area… there could be other insects or animals too, which is a threat to him,” Ms Nazari said. Nine news.

‘It is the greatest trauma of my life, that I have not seen him for so many days, that I have not been able to talk to him for so many days.

“I look at his pictures all the time and pray to God that he comes back, he comes back soon.”

She said her brother dreams of becoming a neurosurgeon and remains hopeful that authorities will bring him back to safety.

Hadi Nazari, who turns 23 on New Year's Eve, separated from the group on the mountain while taking photos

Hadi Nazari, who turns 23 on New Year’s Eve, separated from the group on the mountain while taking photos

“I’m sure if he survives he’ll do a lot… he’s very intelligent,” she said.

“We just want them to find him safe for us, that’s all.”

The search involved multiple authorities including Goulburn Police Rescue, SES, NSW Ambulance, VRA Rescue, Polair and the NSW Parks and Wildlife Service.

So far, air and ground searches have revealed no traces of the young man.

Mrs Naziri told the ABC her brother is an avid photographer, which caused his initial separation from the group.

“He said, ‘I’m going to stay behind and take some pictures,’” she said.

“So his friends came down and made their breakfast and stuff, and when they went back he didn’t come until two o’clock.”

“We want more people to come, it’s a very vast area, it’s a very densely populated area… more support from all over will speed up the process.”

She said she feared her brother would endure cold nights on the mountainside and that she had read reports of another woman who was bitten by a snake in the mountains and remained missing for thirteen days.

SES Chief Inspector Matthew Price said the trail was at the back of the Kosciuszko main range and was pleased to know Mr Nazari had some experience of bushwalking.